JPS5875118A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To decrease reflected light and to improve the visibility of displays by providing a transparent dielectric layer on the transparent electrode of a transparent substrate, and specifying the relations between the respective optical film thicknesses of the transparent electrode and the layer and design wavelengths. CONSTITUTION:A transparent electrode 3 having a reflective index n1 and a film thickness d1 is provided on a transparent substrate 2 having a refractive index n0. A transparent dielectric layer 4 of which the refractive index changes continuously from n2 to n3 in the direction (d) of thickness is formed thereon. A liquid crystal 5 of a refractive index nLC is provided on the layer 4. Here the relations between the products of the respective refractive indices and film thicknesses of the electrode 3 and the layer 4, that is, the optical film thicknesses, and the design wavelengths used are specified like the inequalities (I), (II). When the design wavelength lambda is set at 520mmu, and N1=N2=1, the reflection characteristics in the visible region of the electrode substrate are shown by a curve 51. The reflection thereof is <=2% and the liquid crystal display element of good visibility is obtained.

Description

[Detailed description of the invention] The present invention relates to improvements in liquid crystal display elements.

There are many display methods using liquid crystals, including DAM (dynamic scattering mode), TN (twisted nematic), and guest-host mode.
It is indicated by a pair of hands that sandwich the crystal and apply a voltage.

In any of the above liquid crystal display systems, at least one electrode is made up of a VS electrode, but because the material of the transparent electrode has a high refractive index, the light emitted from the transparent electrode pattern is strong. reflected.

This reflected light is disturbing to observers and significantly reduces the quality and contrast of the liquid crystal display cell.In addition, if the reflected light is strong, it may create an illusion that it is in operation even when it is inactive. ■ζ〇--Japanese Patent Laid-Open No. 56-52789 is known as a proposal for reducing the amount of reflected light from the electrode pattern. In this proposal, the reflectance is reduced by providing a mold layer with a uniform refractive index to a required thickness on a transparent electrode. However, with this method, it is difficult to sufficiently remove harmful reflected light in the visible wavelength range of 40011μ to 700111μ. It is an object of the present invention to provide a liquid crystal display element that can be removed satisfactorily.

In the liquid crystal display element according to the present invention, the structure of the electrode substrate having a transparent electrode disposed as at least one electrode includes a transparent electrode on the transparent substrate, and further a transparent electrode on the cough transparent electrode between the transparent electrode and the transparent substrate. In order to mainly remove reflected light generated by If the refractive index of the dielectric thin film layer is 1%, the optical thickness of each layer is α1・(2N,−1)・λ
≦Town d1≦0.15・(2N,-1)・λ0.4・N,
・λ≦ta(d)・Δd≦0.6・N, ・λHowever, λ: Needle setting technique length N,, N, ; The above purpose is achieved by satisfying any positive integer. It is.

Furthermore, in the liquid crystal display element according to the present invention, it is possible to perform a treatment for orienting the liquid crystal on the surface of the dielectric thin film layer on the liquid crystal side. Even if such a treatment is applied to the dielectric thin film layer, it still has a sufficient anti-reflection function. The dielectric thin film layer of the liquid crystal TC town has a rumored relationship with the liquid crystal, which achieves excellent reflection performance.

This Ql'jKIIl will be explained in detail below.

FIG. 81 is a cross-sectional view of an embodiment of a liquid crystal display element according to the present invention. Figure 1 is twisted! This is a type of liquid crystal display element using a tick. 1 is an electrode substrate having a transparent electrode according to the present invention, a vertical substrate is a transparent substrate 2, a transparent electrode 3 provided on the transparent substrate, and a transparent electrode 3 provided on the top of the pattern pattern. It consists of a dielectric thin film layer 4 provided in order to reduce harmful reflected light generated by the interference between the transparent electrode 2 and the recording substrate 3. A liquid crystal S is provided between the iron electrode substrates, and two linear polarizing plates (6, 7) are arranged with the above-mentioned nine materials in between so that their polarization axes are perpendicular to each other. For convenience, Figure 1 does not show spacers or sealants that maintain one liquid crystal. 5I shown in Figure 1! In this example, a dielectric thin film layer for anti-reflection was applied to both electrode substrates, but even if it is provided on either electrode substrate, compared to conventional display elements, the dielectric thin film layer is applied to both electrode substrates. A liquid crystal display element with reduced reflected light can be obtained.

a12aa is a diagram showing the electrode substrate according to the present invention shown in FIG. 1; is the refractive index of the transparent group I[2, ts is the refractive index of the transparent electrode 30, %lFi is the refractive index of the transparent electrode 3 of the dielectric thin film layer 4, and m is the refraction of the liquid crystal 5 side of the dielectric thin film layer 4. 4 indicates the refractive index of the liquid crystal 5, sd, td, the geometric thickness of the transparent electrode 3, and 4 indicates the geometric thickness of the dielectric thin film layer 4. In this application, transparent In order to reduce the light reflected by the electrodes, a #electrode thin film layer is especially provided as an anti-reflection layer. By optimizing the amplitude and phase conditions of the dielectric thin film layer and liquid crystal, the reflected light from the transparent electrode pattern can be reduced.

The refractive index of the dielectric thin film layer 4 changes depending on its thickness direction, and the manner in which the refractive index changes is shown in FIG. 3(A).
As shown in Figure 3(B), the refracted heavy electric current changes continuously in the film thickness direction (f8 direction), or as shown in Figure 3 (B), the refracted heavy electric current changes in a stepwise manner of at least three or more steps. The optical thickness of each layer is expressed as: 4 mg for the transparent electrode 3 and r*le(d)・Δd for the thin electrolyte layer 4. It shows the distribution line of the refractive index in the direction. For example, when the refractive index is step-like, 5(d) becomes a step function. In the present invention, this town d,, r"5(d )・Δd
By providing the relationship K, the reflection prevention of the electrode substrate becomes bright red. However, λ is the design wavelength, N, IN
, is any positive integer. ◎ FIG. 4 is a diagram showing an embodiment of the electrode substrate of the liquid crystal display element of the present invention. The refractive index of the substrate 2 is 1.52, and the refractive index of the transparent electrode 3 is 1.85.
The refractive index of the dielectric thin film layer 40 on the transparent electrode side is 1.85. The refractive index of the liquid crystal side is 1.65, and the refractive index of the liquid crystal 5 is 1.6.

Based on the refractive index relationship shown in FIG. 4, when the design wavelength λ of the equation (1) is set to 520H1fi s N,=approximately 1.

FIG. 5 shows the reflectance If# of the 1q viewing area of the electrode substrate at various optical film thicknesses determined from equation (i) above. Fifth
Table 1 shows the values of the optical film thicknesses 814 e and f'''(')·Δd corresponding to the reflectance characteristics shown in the figure (51 to 55).

11th! As shown in Fig. 5, the reflectance R is approximately 1.5% or less over the visible wavelength range λ, and the variation in reflectance depending on wavelength is small. Similarly, in relation to the refractive index shown in Fig. 4, Taking the design wavelength λ of the above formula (1) as 520 meters, N1 = 2, N, = 1, the reflectance at 59 o'clock town d = 195 town, - (d) · Δd = 260 degrees μ The characteristic curve is shown at 61 in Fig. 6, also N, =
When we take 2, N, = 2, s, dl = 19
511171, the reflectance R is 1.311 or less in the visible range, and the variation amount of the reflectance O with respect to wavelength is also small, showing very excellent reflection characteristics.

In the above-mentioned liquid crystal display element, the transparent substrate 2 has a refractive index of 5° or less. If it is a transparent inorganic material with a refractive index close to , even if its surface is protectively coated with an inorganic material, it can be optically regarded as a transparent substrate with a refractive index of s and 0, and its reflectance will hardly change. Therefore, when the transparent substrate is glass, the alkali ions contained in the glass deteriorate the performance of the liquid crystal, so the surface of the glass substrate
A protective coating is preferably provided with a transparent inorganic material having a refractive index approximately equal to the refractive index of the substrate. For example, a transparent substrate has a refractive index of 1.5.
2, the surface has a refractive index of approximately 1.4.
88i0. It is best to protect it with a transparent inorganic substance.

Examples of materials used in the embodiments of the present invention, including the transparent substrate described above, include soda lime, barium crown, barium flint,
Glass such as heavy barium crown, flint, heavy flint, etc., or plastic such as polymethyl methacrylate (acrylic), polyester, polystyrene, polycarbonate, etc., and the transparent electrode 3 is In, O, 8n.

"ham K 8n added, dielectric thin film layer 4
as 8tO, OeO,, TtO, *) J, O,,
The liquid crystal 5 is a nematic liquid crystal, etc. made of polyimide resin, polyamideimide resin, etc.

Furthermore, the dielectric thin film layer 4 can maintain the required optical performance even if its surface is subjected to an alignment treatment such as rubbing in order to align the liquid crystal. Moreover, the dielectric thin film layer 4
Ground treatment to strengthen the adhesion between the transparent electrode 3 and the transparent electrode 3,
For example, even if the film is treated with a silane agent, the required optical performance can be obtained.

Further, as a method for applying the transparent electrode 3 and the dielectric thin film layer 4,
Vacuum evaporation, sputtering, ion plating, dip coating, spinner coating, OVD method (Kenkar paper deposition method), etc. @ Changing the refractive index in the thickness direction of the Joki mold thin film layer 4 As for the method.

(:) A method of changing the substrate temperature during vapor deposition, residual gas components, etc. (or) A method of implanting desired ions into a thin film layer (+t+)
There is a method of spinner coating while changing the substrate temperature (:V), a method of forming a film by OVD coating without changing the substrate temperature, etc. As mentioned above, in the liquid crystal display element according to the present invention,
Not only can the reflectance of the electrode pattern be significantly reduced, but
The reason why the refractive index of the dielectric thin film layer decreases from the electrode side to the liquid crystal side is because the density of the dielectric thin film layer decreases on the liquid crystal side.

[Brief explanation of drawings]

Figure 1 is a diagram schematically showing an embodiment of the liquid crystal display element according to the present invention, Figure 2 is a diagram showing changes in the refractive index of the O#Il electric thin layer of the liquid crystal substrate according to the present invention, and Figure 41 FIG. 6 is a diagram showing one embodiment of the electrode substrate of the liquid crystal display element according to the present invention, and FIG. 6 is a diagram showing the reflectance characteristics of the electrode substrate of various liquid crystal display elements according to the present invention. l... Electrode substrate, 2-... Transparent substrate, 3... Transparent electrode, 4... Dielectric thin film layer, 5-... Liquid crystal, 6.7...
・Polarizing plate, R...Reflectance, λ...Wavelength. Applicant Nakayano 7 Co., Ltd. // 'F'L' * '/ # To 21 Lingliao J direction

Claims (1)

[Claims] (1) At least four electrodes, one of which is a liquid crystal display consisting of a liquid crystal sandwiched between electrode substrates each consisting of a transparent electrode. A transparent electrode is provided on a transparent substrate, and a transparent electric layer whose refraction changes in the thickness direction to reduce reflected light reflected by the transparent electrode is provided on the transparent electrode. Assuming that the refractive index of the transparent electrode is 1%, the geometrical thickness is 1%, the refractive index of the body layer is 5(j), and the geometrical thickness is d8, the respective optical thicknesses are sA and J""a(d)・Δd・0.1-(2Nj-1)-λ≦"s'*≦0.15-(
2N, -1)-λQ, 4-N1-λ≦, /”s(d)m
d≦α6. A liquid crystal display element characterized in that N, , λ, where λ is a design wavelength, and N, , N is any positive integer.